One type of traditional decorative tile comprises a square slab having one ornamented face. The ornamentation is usually in the form of relief sculpture, i.e. raised features. Such tiles have been applied directly to a ceiling or suspended from reinforced ceiling grid systems to make decorative ceilings.
Gypsum plaster-based decorative tiles of this type are heavy, bulky and frangible with minimal insulation value. Such tiles generally are made of gypsum plaster in combination with chopped glass or sisal fiber. While other materials may be used in minor amounts as diluents, the major components remain the plaster which provides compressive strength and structure and the glass or sisal fiber which is added for tensile and break strength. Such tiles can be molded to provide decorative three dimensional designs of intricate, sharply defined configurations. Due to the high weight and relative difficulty in manufacturing such tiles as compared to other building materials, molded tiles or slabs of plaster-based material have never gained widespread popularity in the construction of decorative ceilings.
Mineral wool-based ceiling tiles have been used in conjunction with a hanging grid system to provide a relatively inexpensive, lightweight ceiling tile which can be put in place quickly. Ceilings of this type are not aesthetically pleasing because the designs possible for these ceiling tiles are extremely limited, and the painted metal grid system is often discernible as a separate element. This invention provides a tile which is light in weight like such a mineral wool-based tile but has an ornate decorative face like a traditional gypsum-based tile.
Materials such as gypsum plaster, glass fibers, vermiculite and perlite have been previously used in various types of building materials such as wallboard. See, for example, Bruce U.S. Pat. No. 4,403,006 issued Sept. 6, 1983, Dean U.S. Pat. No. 3,376,147 issued Apr. 2, 1968, Ordell U.S. Pat. No. 2,853,394 issued Sept. 23, 1958, Seybold U.S. Pat. No. 2,705,197 and Marczinczek U.S. Pat. No. 1,574,252 issued Feb. 23, 1926. Artifically produced substances such as fly-ash, which have a similar chemical composition to natural volcanic materials such as vermiculite and perlite, have also been used in such construction materials. See, for example, Kurz U.S. Pat. No. 4,087,285 issued May 2, 1978, and Chemical Abstracts 90: 108,937h, "High Strength Gupsum Products", 90: 757,04Z, "Activation of Fly-Ash For Mortar and Concrete", 87: 121,882u, "Effective Calcium Hydroxide and Gymsum on the Pozzuolanic Properties of Fly-Ash II" and 86: 160,087n, "Calcium Hydroxide and Plaster-Their Effects on Pozzuolanic Properties of Fly-Ash". According to one aspect of the invention, materials such as vermiculite and perlite in expanded form are used in combination with plaster and fibers in a decorative ceiling tile quite different from known gypsum wallboards.